Council of CBSEAffiliated School in the Gulf. PHYSICS Max.Marks : 70

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1 /' Council of CBSEAffiliated School in the Gulf -----~ ~ The G"LarSanodaya"Exani-jnation 20DS--- Class- XI.~ PHYSICS Max.Marks : 70 Time: 3 hours :Jeneral instructions: 1. All questions are compulsory. 2. There is no overall choi~e, However, an internal choice has been provided in one question of two marks, one question of three marks and one question of five marks. You have to attempt only one of the choices in such questions. 3. Questions numbers 1 to 8 are very short answer questions, carrying 1 mark each. 4. Question numbers 9 to 18 are short answer questions, carrying 2 marks each. 5. Question numbers 19to 27 are short answer questions, carrying 3 marks each. 6. Question numbers 28 to 30 are long answer questions, carrying 5 marks each. 7. Use of calculators is not permitted. However you may use log tables, if necessary. 8. You may use the following values of physical constants, wherever necessary: 9. Value of acceleration due to gravity = 10 ms 2 Questions:,~I 1. The period of oscillation of the bob of a simple pendulum is given by = 2:n:.J~. What is the percentage error in the determination of its period, if the length of the pendulum is measured with x % {error?.' 2. The distance travelled by a moving object is proportional to time. Is the motion accelerated? Give reason for your answer. 3. A steel ball of radius { r 'falls with the same terminal velocity in a high viscous fluid (A', as another ball of radius '2rJ in liquid B. What is the ratio of coefficient of viscosity of the two liquids A and B? 4. At what position is the kinetic energy of a particle executing SHM i) maximum and ii) minimum. 5:' Name the different J stages of a Carnot's cycle.

2 6. A bullet of 'm' gram is fired from a rifle with muzzle speed of 'v' ms'l. Find the work done on the bullet during the course of firing the bullet?,.. 7. The velocity of sound in air is 332 ms'l. The frequency of fundamental note of an open end organ' pipe is Find the length of the pipe. 8. Two bubbles of same liquid are in the. ratio 2:3.Compare the excess of pressure inside these bubbles. 9. i) At which of the points marked in the distance-time graph of a moving object in the figure, the speed is minimum. Give reason for your answer. ii) Under what condition the relative velocity is zero with another object? ~ Show that the resultant of two equal magnitude vectors bisects the angle between the two vectors. Time. in Seconds 10. Tbe_position of 2Kg mass moving along a straight line is given by x = - 5 t t - 6. Find the force acting on.the particle and the momentum of it at t = 2 second. f 11. A ball is thrown vertically up with a velocity of 20ms 1 from the top of a building of 25m high from the ground. I) How high the ball will reach? ii) How long will it take the ball to reach the ground? p' r -x I ( 2 2 '. 12. Using the relation 11 == 4 v 1 ). Find the dimensions of 'r( Given that 'p' is the pressure difference between the ends of a tube through which liquid is discharged, 'r' is the radius of the pipe I 'I' is the length of the pipe and 'v' is the velocity of liquid at a perpendicular distance 'x' from the central axis of the pipe. 13. A light body and a heavy body have equal kinetic energy. Will they possess equal linear momentum? Explain your answer.

3 % c0a ball falls under gravity from a height of 10m with an initial velocity IU'. It collides with the found and loses 50% Of its kinetic energy during the collision and then rise back to the same height. ~. the initiql velocity. l=ivd ' ~. Two heavy spheres of mass 100Kg 'and 400Kg are placed 2m apart in air on a horizontal table. 'hat is the gravitational field strength at the midpoint of the line joining the centre of the spheres? 1. If the volume of a metal block changes by 0.12% on heating it through 20 C.Find the coefficient : linear expansion? rt Two vessels A and B of capacity in the ratio 1:2, contain the same mass of hydrogen ~spectively at the same temperature. ompare i) the average kinetic energy of hydrogen and oxygen molecules. '- ii) The root.. mean square speed of the molecules of hydrogen and oxygen molecules. the ratio of their molecular mass is 1:16 ) and oxygen I 8. List any four differences between stationary and travelling waves. ~; 9. Two trucks of mass ml and m2 are accelerated uniformly at the same rate. The second truck ravels for twice the time of the first truck. What is i) the ratio of the force acting on them ii) the ratio of their final velocity of the trucks? iii) the ratio of the distance covered by them.? ZOo In the absence of external torque acting on a body of mass 1m' which turns about an axis, Explain low do the following physical quantities change: I). Angular acceleration. ii). Angular momentum. ) Hi). Angular speed. 21. What is the force acting ~etween two spheres of mass 1M' and 1m' with their centres separated by (). distance Ir' apart in air? Also calculate the force between them ) if the mass of each sphere is doubled and the distance between them is halved? the spheres are placed at the distance apart in a liquid whose density is 800 times to that of air? 'J

4 22. a). Sketch the stress-strain graph for a metal wire which is subjected to a varying load. b). Mark on the graph i) plastic region, and ii) residual strain. l c) How is Young's modulus of elasticity of the material of the wire is determined from the graph? 23. a). Among oxygen and helium of equal mass, which one will be raised to higher temperature on supplying same quantity of heat and why? ~, b) When ice melts, the change internal energy becomes more than the total energy supplied. Why? (J-' c). It is not possible to construct a heat engine of 100% efficiency. An object of In' particles each of mass.'m' rotates about an axis with angular velocity 'co'.find expression for the rotational kinetic energy of the object. Hence define moment of inertia of the object about the axis of rotation. 25. a) The diameter of a stretched wire between two fixed points is doubled. What is the effect on the speed of the wave setup in the wire? / b). The speed. of sound wave in C)irat S.T.P~is'x' metres per second. What is the speed of sound in,... vwhen the pressure is incr.eased to 4 atmosphere. c). The speed of longitudinal wave in solids is much greater than that in gases. Why? 26. A graph p~v verses P for 'm' grams of oxygen gas at two different temperatures is as shown. (Molecular mass of oxygen = 32 grams, gas constant J mole'lk'l i) What does the dotted line signify? ii). Which one of the graphs is drawn for higher temperature? iii). What is the value of p. V,where the curves meet on the Y-axis? T! p The force constants of two springs 'A' and 'B' are ka and kb, where ka> kb To which spring more work is done,if i). they are stretched ' by the force of equal magnitude? ii). They are stretched to the same extent? ~. 27. A body of mass 'M' at rest is struck elastically by a body of mass 'm'. Show that the fraction of kinetic energy of mass 'm' transferred to stationary mass is f M+m 4 M m '" )'V

5 , alia).define instantaneous acceleration of a moving object. b). Show that the gradient of velocity - time graph gives the acceleration of a moving object. c). D,raw dj;;placement - time graph to represent following i) uniformly accelerated motion, ii) uniformly retarded motion and iii) uniform motion d). Find expression for the distance covered by a uniformly accelerated object during nth second of motion. '1-q,~). Define a projectile. b).show that the path of an oblique projectile is parabolic. c). Find relation between range and maximum height of a projectile 1 :..- 1 '1 in terms of angle of projection. R~ State and prove Bernoulli's theorem with the help of a diagram. "/J.. State Newton's formula for the viscous force acting between two layers of fluid and hence define e coefficient of viscosity of fluid. Find expression f~r the terminal velocity of a solid sphere falling through a high viscous fluid. ) Show graphically the variation velocity of the sphere with the time of fall. ~(J. a). State the law of conservation of momentum. Deduce Newton's third law of motion from the w of conservation of momentum. b.) Define impulse. Show that the change in momentum of an object is equal to the impulse. a. State Newton's third law of motion. Find expression for the recoil velocity.of a gun, when a bullet is fired from it. b. State any two laws of friction. c. Mention any two methods of reducing friction. / 'V